Hook Fastener and Methods for Manufacturing Same

ABSTRACT

A hook fastener includes a stem having two lateral edges, a first surface, and a second surface. A cap extends from an upper end of the stem, and the cap includes an upper surface, a first end, a second end, and a pair of overhanging portions. The upper surface of the cap is sloped between the first end and the second end. The first and second ends are at opposite longitudinal ends of the cap, and each overhanging portion extends in a lateral direction from the stem.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to and claims priority benefits from U.S.Provisional Application Ser. No. 62/238,350 (“the '350 application”),filed on Oct. 7, 2015, entitled Hook Fastener and Method forManufacturing Same. The '350 application is hereby incorporated in itsentirety by this reference.

FIELD OF THE INVENTION

This invention relates to hook fasteners for hook and loop attachmentdevices and for increasing insertability and increasing the forcesrequired for disengaging hook and loop attachment devices.

BACKGROUND

Hook and loop attachment devices are utilized for a wide variety ofproducts including, for example, clothing, shoes, diapers (for bothchildren and adults), luggage, and throughout the automotive andaerospace industries. The design of hook and loop attachment devices forsome products may include inefficiencies or inadequate attachmentstrength that leads to unintended disengagement.

In certain situations, it may be desirable to design hook and loopattachment devices to maximize strength and perceived strength whenusing and/or disengaging the hook and loop attachment devices.

SUMMARY

The terms “invention,” “the invention,” “this invention” and “thepresent invention” used in this patent are intended to refer broadly toall of the subject matter of this patent and the patent claims below.Statements containing these terms should be understood not to limit thesubject matter described herein or to limit the meaning or scope of thepatent claims below. Versions of the invention covered by this patentare defined by the claims below, not this summary. This summary is ahigh-level overview of various aspects of the invention and introducessome of the concepts that are further described in the DetailedDescription section below. This summary is not intended to identify keyor essential features of the claimed subject matter, nor is it intendedto be used in isolation to determine the scope of the claimed subjectmatter. The subject matter should be understood by reference toappropriate portions of the entire specification of this patent, any orall drawings and each claim.

According to certain examples, a hook fastener comprises: a stemcomprising two lateral edges, a first surface, and a second surface, thestem extending from a base surface; a cap that extends from an upper endof the stem, the cap comprising: an upper surface, a first end, a secondend, and a pair of overhanging portions, wherein: the upper surface ofthe cap is sloped between the first end and the second end; the firstand second ends are at opposite longitudinal ends of the cap; and eachoverhanging portion of the pair of overhanging portions extends in alateral direction from the stem.

According to certain examples, a hook fastener comprises: a stemcomprising two lateral edges, the stem extending from a base surface; acap that extends from an upper end of the stem, the cap comprising: anupper surface, a first end, a second end, a first overhanging portion,and a second overhanging portion; and a cavity on an underside of thesecond end of the cap near an interface between the cap and the stem,the cavity penetrating a surface of the hook fastener, wherein the firstand second ends are at opposite longitudinal ends of the cap and thefirst and second overhanging portions extend in opposite lateraldirections from the stem.

According to certain examples, a method of manufacturing hook fastenerscomprises: forming an intermediate component of a hook fastener where alongitudinal axis of a deforming portion of the intermediate componentis tilted at an angle that is approximately 10°-15° from a verticalaxis; passing the intermediate component between a first roller and asecond roller; and deforming the deforming portion of the intermediatecomponent to form a cap, wherein the cap comprises: an upper surface, afirst end, a second end, and at least one overhanging portion, wherein:the upper surface of the cap is sloped between the first end and thesecond end; the first and second ends are at opposite longitudinal endsof the cap; and the at least one overhanging portion extends in alateral direction from the cap.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present disclosure are described indetail below with reference to the following drawing figures:

FIG. 1 is a perspective front view of a hook fastener according tocertain aspects.

FIG. 2 is a front view of the hook fastener of FIG. 1.

FIG. 3 is a top view of the hook fastener of FIG. 1.

FIG. 4 is a side view of the hook fastener of FIG. 1.

FIG. 5 is a perspective top side view of the hook fastener of FIG. 1.

FIG. 6 is a perspective bottom side view of the hook fastener of FIG. 1.

FIG. 7 is a side view of the hook fastener of FIG. 1.

FIG. 8A is a top view of the hook fastener of FIG. 1, shown engaged witha loop.

FIGS. 8B, 8C, and 8D are cross sectional views of the hook fastener ofFIG. 8A.

FIG. 9A is a front view of an intermediate state of the hook fastener ofFIG. 1.

FIG. 9B is a side view of an intermediate state of the hook fastener ofFIG. 1.

FIG. 10 is a schematic view of a manufacturing process for hookfasteners according to certain aspects.

FIG. 11 is a top view of a hook fastener according to certain aspects.

FIG. 12 is a top view of a diaper incorporating hook fasteners accordingto certain aspects.

DETAILED DESCRIPTION

The subject matter of versions of the present invention is describedhere with specificity to meet statutory requirements, but thisdescription is not necessarily intended to limit the scope of theclaims. The claimed subject matter may be embodied in other ways, mayinclude different elements or steps, and may be used in conjunction withother existing or future technologies. This description should not beinterpreted as implying any particular order or arrangement among orbetween various steps or elements except when the order of individualsteps or arrangement of elements is explicitly described.

FIGS. 1-12 depict examples of hook fasteners 100 that are configured toengage a loop or a loop attachment structure. For example, FIG. 8A showsa top view of a hook fastener 100 engaged with a loop attachmentstructure 50. As described below, the geometric features of the hookfastener 100 may be adapted to affect one or more characteristics of theengagement of the hook fastener 100 with the loop attachment structure,such as, but not limited to, ease of attachment, attachment strength, orany other relevant attribute, or otherwise facilitate engagement of thehook fastener 100 with the loop attachment structure.

As shown in FIG. 1, hook fastener 100 includes a cap 101 that extendsfrom an upper part of a stem 201, the stem 201 extending from a basesurface 1. As shown in FIGS. 1-6, the cap 101 includes a first end 102,a second end 103, and two or more overhanging portions. As shown inFIGS. 1 and 2, the two or more overhanging portions may include a firstoverhanging portion 104 and a second overhanging portion 105. In somecases, the first end 102 corresponds to a rear machine direction and thesecond end 103 corresponds to a front machine direction, where the frontmachine direction is a direction in which a product is transportedduring a manufacturing process and the rear machine direction is adirection opposite to the direction in which the product is transportedduring the manufacturing process.

As shown in FIG. 3, the first end 102 and the second end 103 may bepositioned at opposite longitudinal ends of the hook fastener 100 (i.e.,along the X-axis). In some examples, the first end 102 extends a fullwidth of the cap 101 and thus includes parts of the first and secondoverhanging portions 104 and 105 that extend in the rear machinedirection. In some examples, the second end 103 extends a full width ofthe cap 101 and thus includes parts of the first and second overhangingportions 104 and 105 that extend in the front machine direction.

The overhanging portions 104 and 105 may extend in one or moredirections including, for example, the X and/or Y axes shown in FIG. 3.In some examples, the X-axis is approximately parallel to the machinedirection (MD). The Y-axis direction extends along a cross machinedirection (CD). In the illustrated example, the overhanging portions 104and 105 extend from the stem 201 in lateral directions that areapproximately parallel to the Y-axis. As illustrated, the cap 101 may bedistorted and configured so portions of the cap 101 adjacent to thefirst end 102 are curled and/or everted. In some cases, the cap 101being curled and/or everted creates an open region under the overhangingportions 104 and 105 where a loop attachment structure 50 may engage thehook fastener 100 as shown in FIG. 8A.

With reference to FIG. 2, the overhanging portions 104 and 105 mayextend down toward base surface 1 such that angle θ is approximately90°, where angle θ is an angle between a line approximately parallel tothe underside of overhanging portion 104 (or 105) and the side surfaceof stem 201. As illustrated, the side surface of stem 201 may beapproximately vertical. To ensure that loop attachment structures, suchas loop attachment structures 50, can adequately disengage from the hookfastener 100, the overhanging portions 104 and 105 only extend aspecified distance toward base surface 1 (i.e., angle θ may be acute butnot significantly less than) 90°. For example, in some cases, angle θ isbetween approximately 60° and 120°. In some examples, angle θ isapproximately 80°.

The overhanging portion 105 may include one or more generally flatportions 401 on its underside surface, as shown for example in FIG. 6.Similarly, the overhanging portion 104 may include one or more generallyflat portions 401. In some cases, the generally flat portions 401 areapproximately parallel to the base surface 1. In some cases, as shown inFIG. 6, the underside surface of one or both of the overhanging portions104 and 105 may also include a concave portion 402. The concave portion402 may function as a cavity for securing loop attachment structure 50and thus increasing peel strength.

As shown in FIG. 2, in some cases one or both of the overhangingportions 104 and 105 are thicker in the vertical direction than acentral portion of the cap 101 (i.e., the portion of the cap 101 abovethe stem 201).

In some cases, at least a portion of the first end 102 is thicker andhas a greater height than at least a portion of the second end 103. Forexample, as shown in FIG. 4, the first end 102 may include a thickness(extending generally perpendicular to base surface 1) T₁ while thesecond end 103 may include a thickness (extending generallyperpendicular to base surface 1) T₂ that is less than T₁. In particular,the first end 102, which encompasses parts of the overhanging portions104 and 105, may have the thickness T₁, whereas the second end 103,which encompasses parts of the overhanging portions 104 and 105, mayhave the thickness T₂. The thinner and/or lower portion of the secondend 103 enables the loop attachment structure 50 to easily be insertedonto the hook fastener 100. The thicker and/or taller portion of thefirst end 102 increases stiffness of the first end 102 and thereforeincreases peel strength after the loop attachment structure 50 isinserted, as the thick area increases forces required for elasticdeformation of the cap 101 while the thinner/lower portion prevents areduction in the ability to insert the loop attachment structure 50 ontothe hook fastener 100. In addition, the everted, contoured outer surfaceof the cap 101 increases peel strength.

As illustrated in FIGS. 3 and 11, in some cases the cap 101 is generallysymmetric about the X-axis, but not symmetric about the Y-axis. As shownin FIG. 4, at least a portion of the length of the stem 201 is greaterthan the length of the cap 101 (along the X-axis), while, as shown inFIG. 2, the width of the cap 101 is greater than the width of the stem201 (along the Y-axis). This is because the first and second overhangingportions 104 and 105 have sufficient widths (along the Y-axis) to engagewith the corresponding loop attachment structure 50. As shown in FIG. 3,the first and second overhanging portions 104 and 105 have sufficientlengths (along the X-axis) to engage with the corresponding loopattachment structure 50.

As shown in FIG. 4, the stem 201 may include a sloped surface 202, whichincreases in dimension along the X-axis of the stem 201 when movingtoward the base surface 1. There may be an approximately verticalsurface 203 opposite the sloped surface 202 with side surfaces 204extending between the sloped surface 202 and the approximately verticalsurface 203, as shown in FIGS. 1, 2, and 4. In some cases, the angle ofthe sloped surface 202 relative to the base surface 1 is greater thanthe angle of the approximately vertical surface 203 relative to the basesurface 1. In other examples, the surface 203 may be a second slopedsurface which increases a dimension of the stem 201 (along the X-axis)when moving toward the base surface 1. In such examples, the angle ofthe second sloped surface relative to the base surface 1 is less thanthe angle of the sloped surface 202.

As shown in FIG. 5, the cap 101 may include one or more protrusions 301.In some cases, the one or more protrusions 301 define a maximumthickness (see T₁ in FIG. 4), which is greater than a thickness of otherportions of the cap 101 (see T₂ in FIG. 4). The one or more protrusions301 may be a local peak in the contoured upper surface of the cap 101.

As illustrated in FIG. 4, the upper surface of the cap 101 is slopedbetween the first end 102 and the second end 103 such that the first end102 is elevated higher than the second end 103 relative to the basesurface 1. As a result of this sloped upper surface, the loop attachmentstructure 50 (see FIG. 8A), when interfacing with hook fastener 100,will slide toward second end 103 of the cap 101 to facilitate insertionof the loop attachment structure 50 from the second end 103. In someexamples, this surface may slope uniformly and smoothly. In some cases,this surface may be an irregular surface. After the loop attachmentstructure 50 reaches the second end 103, the loop attachment structure50 will engage the second end 103 for a secure attachment. Specifically,in some cases, the loop attachment structure 50 is received within acavity 107 adjacent to an interface between the cap 101 and the stem 201at an underside of the second end 103, as shown in FIG. 7. For example,a portion 51 of the loop attachment structure 50 (FIG. 8A) is receivedwithin the cavity 107. In some cases, cavity 107 is shaped anddimensioned to snuggly receive and secure the loop attachment structure50. In some examples, the hook fastener 100 includes another cavityadjacent to an interface between the cap 101 and the stem 201 at anunderside of the first end 102. The loop attachment structure 50 may beengageably received in the cavity at the first end 102. In someexamples, the loop attachment structure 50 is not received in the cavityat the first end 102.

As shown in the cross-sectional views in FIGS. 8B-8D, the cavity 107 maybe an open area forming an acute angle at an interior-most point in aregion between the cap 101 and the stem 201. As shown in FIGS. 7 and8B-8D, the cavity 107 extends toward the first end 102 of the cap 101such that a channel penetrates the surface of the hook fastener 100,where the channel is shaped and sized to receive the loop attachmentstructure 50. In some cases, a portion of the second end 103 of the cap101 is cantilevered and extends over the cavity 107. While the slope orangle of the sloped surface 202 is approximately constant, the slope ofthe interior surface of the cavity 107 is different from the slope ofsloped surface 202.

FIG. 8B shows a cross sectional view along line A-A′ of FIG. 8A, FIG. 8Cshows a cross sectional view along line B-B′ of FIG. 8A, and FIG. 8Dshows a cross sectional view along line C-C′ of FIG. 8A. In some cases,as shown in FIGS. 7 and 8B-8D, the cavity 107 may include a wedge-shapedregion that changes along the width of the hook fastener 100 (i.e., theY-axis shown in FIG. 3). For example, the shape of the cavity 107 nearthe center of the hook fastener 100 (see 107 b in FIG. 8C) has a smalleropening compared to the shape of the cavity 107 closer to the lateraledges of the hook fastener 100 (see 107 a in FIG. 8B and 107 c from FIG.8D). The smaller opening for cavity 107 b decreases the likelihood ofinadvertent disengagement of the loop attachment structure 50 from thehook fastener 100. Furthermore, due to the narrowed opening for 107 band because the loop attachment structure 50 wedges into the cavity 107,engagement strength between the loop attachment structure 50 and thehook fastener 100 is increased. In addition, because of the shape ofsloped surface 202 of the stem 201, when loop attachment structure 50interfaces with the hook fastener 100, the loop attachment structure 50is guided along the sloped surface 202 to the cavity 107. Therefore, theengagement rate of loop attachment structures 50 attaching to the hookfasteners 100 increases. In some examples, the angle of the slopedsurface 202 of the stem 201 (relative to base surface 1) is within arange from 50° to 80° to facilitate movement of the loop attachmentstructure 50 along the sloped surface 202 into the cavity 107.

A plan view of the second end 103 (see FIG. 3) illustrates that thesecond end 103 is optimized to attach to the loop attachment structure50 because the second end 103 includes a curved edge that has a greaterradius of curvature than the opposite edge of the first end 102. In somecases, as shown in FIG. 3, the outer edges of the cap 101 may include afirst periphery edge 1001 that is different than the second peripheryedge 1002. Each of the first and second overhanging portions 104 and 105may include a tip end portion A arranged at an outermost point distalfrom the stem 201 in the cross machine direction (CD), a first peripheryedge 1001 at the first end 102 with respect to the tip end portion A,and a second periphery edge 1002 at the second end 103 with respect tothe tip end portion A. The first periphery edge 1001 may extend frompoint B₁ to the tip end portion A and the second periphery edge 1002 mayextend from point B₂ to tip end portion A. Point B₁ is a location on thefirst periphery edge 1001 that is generally aligned with a side surface204 of the stem 201. Point B₂ is a location on the second periphery edge1002 that is generally aligned with a side surface 204 of the stem 201.

If the first and second overhanging portions 104 and 105 are divided bya line passing through each tip end portion A (such that the line isapproximately parallel to the Y-axis) to separate each of theoverhanging portions 104, 105 into a first area of the first end of thecap and a second area of the second end of the cap, the first area issmaller than the second area (when viewed from above). The length offirst periphery edge 1001 may be less than the length of the secondperiphery edge 1002. The radius of curvature for at least a portion ofthe first periphery edge 1001 may be smaller than the radius ofcurvature for the second periphery edge 1002. In some cases, when viewedfrom above, the first periphery edge 1001 is generally straight/linearfrom the point B₁ and extends laterally and approximately parallel tothe Y-axis (FIG. 3) or curves at least partially in a direction oppositeof second end 103 and away from the cap 101 (FIG. 11). When viewed fromabove, the second periphery edge 1002 is gently curved from the point B₂to the tip end portion A. Because the tip end portion A of eachoverhanging portion 104, 105 is closer to the first end 102 compared tothe second end 103 and the radius of curvature for a portion of thefirst periphery edge 1001, which extends from the point B₁ toward thetip end portion A, is smaller than the radius of curvature for thesecond periphery edge 1002, peel strength (engagement) may be increased.Disengagement of loop attachment structure 50 from the second peripheryedge 1002 may be easier than disengagement from the first periphery edge1001, but the longer length of second periphery edge 1002 preventsdisengagement.

In some cases, the shape of the cap 101 is configured to be morecomfortable against a user's skin (e.g., a hand or an abdominal area) asthe top surface is inclined and rounded, and the sides surface are alsocurled and rounded.

FIG. 11 shows another example of a hook fastener 100 with a differentshaped cap 101. Although some of the same reference numbers are used forboth the hook fastener of FIGS. 1-6 and the hook fastener of FIG. 11,the two sets of Figures are not meant to depict the same hook fastener.Furthermore, in some cases, individual features from the two hookfasteners may be combined and/or substituted. In some examples, as shownin FIG. 11, the first periphery edge 1001 extends away from the point B₁at the first end 102 curving in a direction that is at least partiallyin a direction opposite from the second end 103 and the second peripheryedge 1002 extends away from the point B₂ at the second end 103 curvingtoward the first end 102 over the entire length of the second peripheryedge 1002, when viewed from above.

In one exemplary method, hook fasteners 100 are formed from a two-stepcontinuous, injection molding process that includes rolling and applyingheat. In one example, a first step is to form hook fasteners 100 into anintermediate state with a deforming portion 501 (see FIG. 9B). FIG. 9Ashows a front view of intermediate components 100′ of the hook fastener100 before the cap 101 is deformed and FIG. 9B shows a side view of theintermediate components 100′. Each of the intermediate components 100′includes a first protruding portion 201′ which will be the stem 201extending from the base and a second protruding portion 501 (alsoreferred to as a deforming portion 501) having a width narrower than awidth of the first protruding portion 201′ in the machine direction(MD). In the cross machine direction (CD), the dimension of the firstprotruding portion 201′ is approximately equal to the dimension of thesecond protruding portion 501. The intermediate component 100′ may bemolded. For example, synthetic resin may be melted, extruded using a diewheel, and then cooled to mold the intermediate component 100′. In somecases, the hook fastener 100 takes the shape shown in FIG. 9B before itpasses between two rollers, as explained below. As shown in FIG. 9B, thedeforming portion 501 may be tilted in a rear machine direction at anangle φ that is approximately 10°-15° from a center line 511 of thefirst protruding portion 201′ extending in an approximately verticaldirection. In addition, the first protruding portion 201′ may include acenter line 511 and the deforming portion 501 may include a deformingcenter line 512. In some cases, the tilt of the deforming portion 501may affect the final thickness of cap 101 (e.g., see T₁ and T₂ in FIG.4) and/or the contour of sloped surface 202. The first protrudingportion 201′ may include a pair of upper surfaces 207′, which are onboth sides of the deforming portion 501 in the machine direction. Theupper surface 207′ on the front machine side (e.g., left side in FIG.9B) is longer than the upper surface 207′ on the rear machine side(e.g., right side in FIG. 9B). In some cases, the length of the uppersurfaces 207′ of the first protruding portion 201′ may affect the sizeof the cavity 107.

As shown in FIG. 10, an exemplary process for manufacturing hookfasteners 100 may include two rollers 701 and 702, where, in a secondstep, the intermediate components 100′ of the hook fasteners 100 passbetween the two rollers such that the deforming portion 501 is deformedinto the cap 101. The first protruding portion 201′ is not substantiallydeformed and becomes the stem 201 directly. As described above, the cap101 is formed when the intermediate components 100′ of the hookfasteners 100 pass between the two rollers and the deforming portion 501is deformed by the rollers. In some examples, one or both of the rollersare heated. In some cases, the first roller 701 is heated and has afirst speed S₁ and the second roller 702 has a second speed S₂. The twospeeds S₁, S₂ may be the same or may be different. In some cases, thefirst speed S₁ is greater than the second speed S₂. In some cases, thefirst speed S₁ is 5% to 25% greater than second speed S₂, although anysuitable speed differential may be used.

FIG. 12 shows an example of a diaper incorporating one or more hookfasteners 100 on a tab of the diaper. For illustration purposes, FIG. 12includes a representation of hook fasteners 100 that are drawnschematically and are not drawn to scale. In some cases, the hookfasteners 100 are arranged as shown in 901 while in other cases, thehook fasteners 100 are arranged as shown in 902. In FIG. 12, 901 showsan example where the first and second overhanging portions extend in alongitudinal direction of a tab T to which the hook fastener 100 isattached such that the first end is arranged at one side in a widthdirection of the tab T and the second end is arranged at opposite sideto the one side. In FIG. 12, 902 shows an example where the first endand the second end are arranged opposite to the example of 901. The hookfasteners can be arranged in any suitable orientation, however, and arenot limited those arrangements shown in FIG. 12. For example, the hookfastener structures 100 are arranged in a combination of thearrangements shown in 901 and 902. The hook fasteners also can bepositioned on any suitable structure and are not limited to use withdiapers and/or tabs on diapers.

The components of the hook fasteners 100 may be formed of materialsincluding, but not limited to, non-woven polypropylene, other non-wovenmaterials, woven materials, other plastic materials, thermoplastic,metallic materials, other composite materials, cotton, wool, syntheticfabric, or other similar materials.

Different arrangements of the components depicted in the drawings ordescribed above, as well as components and steps not shown or describedare possible. Similarly, some features and sub-combinations are usefuland may be employed without reference to other features andsub-combinations. Cases of the invention have been described forillustrative and not restrictive purposes, and alternative cases willbecome apparent to readers of this patent. Accordingly, the presentinvention is not limited to the cases described above or depicted in thedrawings, and various cases and modifications may be made withoutdeparting from the scope of the claims below.

That which is claimed is:
 1. A hook fastener comprising: a stemcomprising two lateral edges, a first surface, and a second surface, thestem extending from a base surface; a cap that extends from an upper endof the stem, the cap comprising: an upper surface, a first end, a secondend, and a pair of overhanging portions; wherein: the upper surface ofthe cap is sloped between the first end and the second end; the firstand second ends are at opposite longitudinal ends of the cap; and eachoverhanging portion of the pair of overhanging portions extends in alateral direction from the stem.
 2. The hook fastener of claim 1,wherein the cap comprises a cavity on an underside of the second end ofthe cap near an interface between the cap and the stem, the cavityextending beyond the second surface of the stem toward an interior ofthe hook fastener and toward the first end of the cap.
 3. The hookfastener of claim 2, wherein the cavity forms an acute angle at aninterior-most point.
 4. The hook fastener of claim 3, wherein the cavitycomprises a wide opening near each of the two lateral edges of the stemand a narrow opening near a center of the stem.
 5. The hook fastener ofclaim 1, wherein the first end is thicker than the second end.
 6. Thehook fastener of claim 1, wherein the pair of overhanging portionscomprises a first overhanging portion extending in a first lateraldirection and a second overhanging portion extending in a second lateraldirection opposite the first lateral direction.
 7. The hook fastener ofclaim 6, wherein each of the first and second overhanging portionscomprises an open region underneath the overhanging portion configuredto engage a loop attachment structure.
 8. The hook fastener of claim 6,wherein each of the first and second overhanging portions comprises anunderside surface that includes a generally flat portion that isapproximately parallel to the base surface.
 9. The hook fastener ofclaim 1, wherein: each overhanging portion of the pair of overhangingportions comprises a tip end portion at an outermost point in thelateral direction, a first periphery edge at the first end, and a secondperiphery edge at the second end; and a length of the first peripheryedge is less than a length of the second periphery edge.
 10. The hookfastener of claim 9, wherein: each overhanging portion of the pair ofoverhanging portions is divided by a line that is approximately parallelto the lateral direction and passes through each tip end portion toseparate each overhanging portion into (i) a first area of the first endof the cap and (ii) a second area of the second end of the cap; and thefirst area is smaller than the second area.
 11. The hook fastener ofclaim 9, wherein a portion of the first periphery edge has a radius ofcurvature that is less than a radius of curvature of a portion of thesecond periphery edge.
 12. The hook fastener of claim 9, wherein thefirst periphery edge comprises a portion that extends generally linearlyin the lateral direction from a first point toward the tip end portionand the second periphery edge comprises a radius of curvature thatextends from a second point to the tip end portion.
 13. The hookfastener of claim 9, wherein the first periphery edge comprises a firstradius of curvature that curves at least partially in a directionopposite of the second end and the second periphery edge comprises asecond radius of curvature that is larger than the first radius ofcurvature.
 14. A hook fastener comprising: a stem comprising two lateraledges, the stem extending from a base surface; a cap that extends froman upper end of the stem, the cap comprising: an upper surface, a firstend, a second end, a first overhanging portion, and a second overhangingportion; and a cavity on an underside of the second end of the cap nearan interface between the cap and the stem, the cavity penetrating asurface of the hook fastener, wherein: the first and second ends are atopposite longitudinal ends of the cap; and the first and secondoverhanging portions extend in opposite lateral directions from thestem.
 15. The hook fastener of claim 14, wherein the cavity forms anacute angle at an interior-most point.
 16. The hook fastener of claim15, wherein the cavity comprises a wide opening near each of the twolateral edges of the stem and a narrow opening near a center of thestem.
 17. The hook fastener of claim 14, wherein the first end isthicker than the second end.
 18. The hook fastener of claim 14, wherein:each of the first and second overhanging portions comprises a tip endportion at an outermost point in the lateral direction, a firstperiphery edge of the first end and extending from a first point to thetip end portion, and a second periphery edge of the second end andextending from a second point to the tip end portion; and a length ofthe first periphery edge is less than a length of the second peripheryedge.
 19. A method of manufacturing hook fasteners, the methodcomprising: forming an intermediate component of a hook fastener where alongitudinal axis of a deforming portion of the intermediate componentis tilted at an angle that is approximately 10°-15° from a verticalaxis; passing the intermediate component between a first roller and asecond roller; and deforming the deforming portion of the intermediatecomponent to form a cap, wherein the cap comprises: an upper surface, afirst end, a second end, and at least one overhanging portion, wherein:the upper surface of the cap is sloped between the first end and thesecond end; the first and second ends are at opposite longitudinal endsof the cap; and the at least one overhanging portion extends in alateral direction from the cap.
 20. The method of claim 19, furthercomprising heating the first roller.
 21. The method of claim 19, furthercomprising spinning the first roller at a first speed and spinning thesecond roller at a second speed, wherein the first speed is 5% to 25%greater than the second speed.